8 Pruning Mistakes That Can Kill Your Trees

Pruning keeps trees healthy, but the wrong approach can do more harm than good. We’ve seen too many homeowners in Northern Virginia make avoidable pruning mistakes that lead to costly damage – or even tree removal. Avoid these pruning techniques to keep your trees thriving.

Key Takeaways:

• Professional help is essential for pruning large trees, those near power lines, or when specialized equipment is needed, as DIY attempts can be dangerous and potentially fatal.
• Making improper cuts (like flush cuts, stub cuts, or heading cuts) or topping trees can severely damage health and lead to weak growth patterns.
• Winter trimming is generally best for most trees; save pruning your spring-flowering ornamentals until after they bloom.
• Never remove more than 25 percent of a tree’s canopy at once, as over-pruning prevents trees from getting necessary nutrients through photosynthesis.
• Using the right tools, making clean cuts, and allowing natural healing (without wound dressings) are essential for successful pruning and long-term tree health.

8 Pruning Mistakes to Avoid to Protect Your Tree

Tree pruning can help your trees thrive, but only when done right. As we try to increase the urban canopies in places like Arlington, keeping trees in peak condition becomes even more important.

It can take a lifetime to master the delicate art of pruning. To help you get up to speed, we’ll identify some common mistakes homeowners make when trimming trees and teach you how to avoid them.

PRO TIP: If you’d like to learn more about pruning in Northern Virginia, see our previous articles on the subject:

• When & How to Prune Fruit Trees in Northern Virginia
• Dangers of Untrimmed Trees in Northern Virginia
• When Shouldn’t You Prune or Remove Trees Yourself?

1. Performing the Wrong Pruning Cuts

Pruning isn’t about just making arbitrary cuts and calling it a day. Arborists make specific cuts to limit the tree’s stress and allow it to recover from the injury. Some pruning methods to avoid include:

• Flush Cuts: As the name implies, a flush cut removes the limb right up to the branch collar (where the branch meets the trunk). The tree is unable to form a callus and will struggle to heal.
• Stub Cuts: Stub cuts leave enough of a branch remaining that the tree cannot correctly seal the wound. Generally speaking, you shouldn’t be able to hang your hard hat from the stub that’s left after pruning.
• Heading Cuts: Cutting a branch at a random point leaves the tree vulnerable to pests and disease. In response, the tree produces weak, excessive growth, which can lead to long-term structural issues.

Tree topping is a discredited practice that harms your trees. Avoid doing it to your trees or working with a company advertising the service.

2. Topping the Tree

Tree topping is picking a line in the canopy and cutting everything above it. While it sounds like an effective way to make a tree shorter and more manageable, it will likely have the opposite effect and actually harm the tree and potentially kill it.

“Tree topping is an incredibly traumatic experience for the tree. To counteract this trauma and the loss of leaves that aid in photosynthesis, the tree will produce lots of rapid and ugly growth called water sprouts. To maintain the size, you’ll need to constantly remove these water sprouts.” – Wiley Holland, Green Vista Arborist

A reputable company will never perform tree topping, as it is a thoroughly discredited service.

3. Pruning Trees Best Left to Professionals

While pruning a small ornamental may not be too difficult if you have the knowledge and equipment, some trees are too dangerous to trim without professional help. Some of the trees best left to the pros include:

• Trees Near Power Lines: Trimming trees near power lines is incredibly dangerous, and it can lead to fatal accidents, like the one in Fairfax in 2022. A company will work with the utility company to shut off power to safely work on the tree.
• Trees with Large Branches: Northern Virginia municipalities, like McLean, have plenty of large, historic trees. Trimming these large branches is dangerous for you and the tree, as you likely won’t have the necessary safety equipment to do the job correctly. You’ll also have difficulty disposing of these large branches without a woodchipper.
• Large and Overgrown Trees: While a homeowner will be able to reach some branches from the ground, it could be nearly impossible to prune branches that are 50 feet in the air without the right equipment. A professional company has access to bucket trucks and other methods to safely reach the upper portions of the tree.

4. Mistiming Your Tree Pruning

Just as important as how you prune is when you do it. Pruning during the fall causes the tree to put out new growth that will likely not survive the winter, wasting the tree’s energy. And trimming in the summer can leave more vulnerable species at risk of attacks from pests. In most cases, winter is the best season to prune because trees are dormant, reducing stress and the risk of pests or disease.

However, spring-flowering ornamentals, like flowering dogwoods, develop their flowers on old wood each year. Pruning them in the winter will cut off buds and harm the aesthetics of the tree in the spring. Instead, trim them in the spring after they finish blooming.

5. Over-Pruning the Tree

Pruning should always be limited to what a tree needs. Take a little bit off the tree at a time rather than removing large portions all at once. Even if a tree is overgrown, it still relies on the leaves of its branches for photosynthesis.

The maximum amount we recommend trimming at once is 25 percent of the canopy, though less is always better.

6. Using the Wrong or Poorly-Maintained Tools

Proper trimming requires a variety of tools. A typical pruning kit for a landscape includes loppers, pole saws, and chainsaws. Each tool is best suited for different types of branches. Trying to cut through a large branch with loppers is just as difficult as attempting to prune a small ornamental tree with a large chainsaw.

In addition to having the right tools, you’ll need to ensure they are in good working order. Loppers or pole saws will dull as you cut. Trimming is best with sharp tools that can make precise cuts.

If you don’t have the right tools for the job, consider having a professional handle the job to avoid damaging your tree.

7. Damaging a Tree’s Bark

Improper tree pruning can damage a tree’s bark. Bark protects a tree from external threats like extreme weather, insects, and diseases. A tree may be able to recover from a small amount of missing bark if the damage is exclusively in the outer layer. However, damage to the interior bark can lead to a weak spot.

Trimming can end up damaging the bark in two ways:

• Falling Branches: If you prune a branch in the upper canopy and let it fall, it can rip other branches off the tree on the way down. These broken branches will likely tear off the tree’s bark with them.
• Improper Removal of Large Branches: Trying to remove a large branch with one cut can cause it to snap off and tear the bark. Instead, use the three-cut method to avoid damaging the bark.

8. Using a Wound Dressing

Since pruning opens up wounds on your trees, you may think dressing the wound or applying paint over it will help it heal faster. Unfortunately, this has the opposite effect.

Wound dressings can trap moisture and cause decay in your tree. Allow your tree to heal naturally rather than trying to apply paint or any other wound dressing.

Frequently Asked Questions About Tree Pruning

With a complicated subject like pruning, we always get questions from homeowners about the service and how best to perform it for their trees. We’ve answered some of the common questions below:

Can I prune my tree a little bit at a time over several months?

No, do all the pruning for a season in one session. Your trees need time to recover from injuries, and constant trimming will not allow them proper healing time.

Should I prune storm damage immediately or wait until the winter?

Damaged branches do not always end up on the ground. Some remain in the canopy, and others remain partially attached. Do not wait until winter to prune these branches; remove them as soon as possible. These branches can damage your property or the rest of the tree.

My neighbor’s tree branch is overhanging on my property. Can I prune it?

Virginia law allows you to prune any overhanging trees up to the property line. However, conferring with your neighbor and asking them to trim the overhanging tree is often best. If you trim the tree yourself and damage it, you may be liable for the damage.

Green Vista Can Help You Prune Your Trees Correctly

Pruning is one of the most essential services you can do for your tree, but it puts them at risk when you do it wrong. With so many ways to harm your trees with pruning, leave the job to a professional.

The team at Green Vista Tree Care has all the tools and expertise to handle pruning of all your Northern Virginia trees. We follow all industry standards to leave your trees healthy and ready to thrive. Call us today at 571-244-3838 or request a quote online for professional trimming.